KYTL 4.1

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4.1 Properties of Minerals


Vocabulary:


Inorganic-can not formed from living things or the remains of living things (dead)
Crystal-a solid in which the atoms are arranged in a pattern that repeats again and again
Element-a substance made up of one single atom
Compound-a substance in which 2 or more elements are chemically mixed together
Mohs hardness scale-a scale used to rank ten minerals from hardest to softest
Streak- the color of a mineral's powder
Luster-used to describe how light reflects on a mineral
Cleavage-a property of a mineral that splits easily along flat surfaces
Fracture-describes how a mineral looks when it breaks irregularly
Fluorescence-the property of the mineral in which the mineral glows under ultraviolet light


Outline:

Summary

  • sphalerite- source of zinc and gallium

What is a Mineral?

  • geologists have identified 3,000 minerals
  • only 100 are common
  • Naturally Occurring
    • to be a mineral, the mineral has to be natural, not man made
    • found from substances in Earth's crust:
      • cement
      • brick
      • steel
      • glass
  • Inorganic
    • can't arise from materials that were once part of a living thing or things
    • For example, coal:
      • forms naturally in the crust
      • comes from remains of plants/animals that were alive a long, long time ago
  • Solid
    • mineral
      • always solid
      • has definite volume
      • has definite shape
    • particles make up solid
      • are clumped together very tightly
      • can't move like particles that make up liquid
  • Crystal Structure
    • particles line up in pattern this process repeats over and over again
    • characteristics of a crystal
      • flat sides, called faces
      • meet at sharp edges and corners
  • Definite Chemical Composition
    • mineral always have certain elements in definite proportions
    • all atoms of same element have the same chemical and physical properties
    • almost all minerals are compounds
    • each compound-own properties

Identifying Minerals

  • each mineral has its own specific property
  • Hardness
    • any mineral can scratch any mineral softer than itself
  • Color
    • can't identify most minerals because some minerals have many colors, like for example quartz
    • malachite is always green
    • azurite is always blue
  • Streak
    • observe streak by rubbing a mineral against piece of unglazed tile (streak plate)
    • minerals can have different colors
    • its streak does't have different colors
  • Luster
    • minerals with metals are often shiny
    • quartz has glassy luster
    • other terms used to describe luster
      • earthy
      • waxy
      • pearly
  • Density
    • no matter size of mineral, density remains the same
    • weight provides rough measure of density
    • to measure, you can:
      • place mineral in water
        • volume of displaced water = volume of mineral
  • Crystal Systems
    • crystals of mineral grows atom by atom to form crystal structure
    • classifed into 6 groups (crystal systems)
    • crystals in open space-almost form perfectly
  • Cleavage and Fracture
    • the way minerals breaks apart- identifies it
    • terms for fracture:
      • shell-shaped (quartz)
      • hackly fracture (pure metals)
      • earthy fracture (soft minerals)
      • uneven fracture (rough, irregular surfaces)
  • Special Properties
    • magnetism occurs naturally sometimes
    • some are radioactive
    • some react chemically to acid
    • some have electrical properties
    • some can glow in ultra-violet light (flouresence)

Diagram

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